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Giese D, Li H, Liu W, Staxäng K, Hodik M, Ladak HM, Agrawal S, Schrott-Fischer A, Glueckert R, Rask-Andersen H. Microanatomy of the human tunnel of Corti structures and cochlear partition-tonotopic variations and transcellular signaling. J Anat 2024. [PMID: 38613211 DOI: 10.1111/joa.14045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 03/22/2024] [Accepted: 03/23/2024] [Indexed: 04/14/2024] Open
Abstract
Auditory sensitivity and frequency resolution depend on the optimal transfer of sound-induced vibrations from the basilar membrane (BM) to the inner hair cells (IHCs), the principal auditory receptors. There remains a paucity of information on how this is accomplished along the frequency range in the human cochlea. Most of the current knowledge is derived either from animal experiments or human tissue processed after death, offering limited structural preservation and optical resolution. In our study, we analyzed the cytoarchitecture of the human cochlear partition at different frequency locations using high-resolution microscopy of uniquely preserved normal human tissue. The results may have clinical implications and increase our understanding of how frequency-dependent acoustic vibrations are carried to human IHCs. A 1-micron-thick plastic-embedded section (mid-modiolar) from a normal human cochlea uniquely preserved at lateral skull base surgery was analyzed using light and transmission electron microscopy (LM, TEM). Frequency locations were estimated using synchrotron radiation phase-contrast imaging (SR-PCI). Archival human tissue prepared for scanning electron microscopy (SEM) and super-resolution structured illumination microscopy (SR-SIM) were also used and compared in this study. Microscopy demonstrated great variations in the dimension and architecture of the human cochlear partition along the frequency range. Pillar cell geometry was closely regulated and depended on the reticular lamina slope and tympanic lip angle. A type II collagen-expressing lamina extended medially from the tympanic lip under the inner sulcus, here named "accessory basilar membrane." It was linked to the tympanic lip and inner pillar foot, and it may contribute to the overall compliance of the cochlear partition. Based on the findings, we speculate on the remarkable microanatomic inflections and geometric relationships which relay different sound-induced vibrations to the IHCs, including their relevance for the evolution of human speech reception and electric stimulation with auditory implants. The inner pillar transcellular microtubule/actin system's role of directly converting vibration energy to the IHC cuticular plate and ciliary bundle is highlighted.
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Affiliation(s)
- Dina Giese
- Department of Surgical Sciences, Otorhinolaryngology and Head and Neck Surgery, Uppsala University, Uppsala, Sweden
| | - Hao Li
- Department of Surgical Sciences, Otorhinolaryngology and Head and Neck Surgery, Uppsala University, Uppsala, Sweden
| | - Wei Liu
- Department of Surgical Sciences, Otorhinolaryngology and Head and Neck Surgery, Uppsala University, Uppsala, Sweden
| | - Karin Staxäng
- The Rudbeck TEM Laboratory, BioVis Platform, Uppsala University, Uppsala, Sweden
| | - Monika Hodik
- The Rudbeck TEM Laboratory, BioVis Platform, Uppsala University, Uppsala, Sweden
| | - Hanif M Ladak
- Department of Medical Biophysics, Western University, London, Ontario, Canada
- Department of Electrical and Computer Engineering, Western University, London, Ontario, Canada
| | - Sumit Agrawal
- Department of Otolaryngology-Head and Neck Surgery, Western University, London, Ontario, Canada
| | - Anneliese Schrott-Fischer
- Inner Ear Laboratory, Department of Otorhinolaryngology, Medical University Innsbruck, Innsbruck, Austria
| | - Rudolf Glueckert
- Inner Ear Laboratory, Department of Otorhinolaryngology, Medical University Innsbruck, Innsbruck, Austria
| | - Helge Rask-Andersen
- Department of Surgical Sciences, Otorhinolaryngology and Head and Neck Surgery, Uppsala University, Uppsala, Sweden
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Bom Braga GO, Parrilli A, Zboray R, Bulatović M, Wagner F. Quantitative Evaluation of the 3D Anatomy of the Human Osseous Spiral Lamina Using MicroCT. J Assoc Res Otolaryngol 2023; 24:441-452. [PMID: 37407801 PMCID: PMC10504225 DOI: 10.1007/s10162-023-00904-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 06/20/2023] [Indexed: 07/07/2023] Open
Abstract
PURPOSE The osseous spiral lamina (OSL) is an inner cochlear bony structure that projects from the modiolus from base to apex, separating the cochlear canal into the scala vestibuli and scala tympani. The porosity of the OSL has recently attracted the attention of scientists due to its potential impact on the overall sound transduction. The bony pillars between the vestibular and tympanic plates of the OSL are not always visible in conventional histopathological studies, so imaging of such structures is usually lacking or incomplete. With this pilot study, we aimed, for the first time, to anatomically demonstrate the OSL in great detail and in 3D. METHODS We measured width, thickness, and porosity of the human OSL by microCT using increasing nominal resolutions up to 2.5-µm voxel size. Additionally, 3D models of the individual plates at the basal and middle turns and the apex were created from the CT datasets. RESULTS We found a constant presence of porosity in both tympanic plate and vestibular plate from basal turn to the apex. The tympanic plate appears to be more porous than vestibular plate in the basal and middle turns, while it is less porous in the apex. Furthermore, the 3D reconstruction allowed the bony pillars that lie between the OSL plates to be observed in great detail. CONCLUSION By enhancing our comprehension of the OSL, we can advance our comprehension of hearing mechanisms and enhance the accuracy and effectiveness of cochlear models.
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Affiliation(s)
- Gabriela O Bom Braga
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Annapaola Parrilli
- Center for X-Ray Analytics, Empa - Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600, Dübendorf, Switzerland.
| | - Robert Zboray
- Center for X-Ray Analytics, Empa - Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600, Dübendorf, Switzerland
| | - Milica Bulatović
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Franca Wagner
- Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
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Hrncirik F, Roberts I, Sevgili I, Swords C, Bance M. Models of Cochlea Used in Cochlear Implant Research: A Review. Ann Biomed Eng 2023; 51:1390-1407. [PMID: 37087541 PMCID: PMC10264527 DOI: 10.1007/s10439-023-03192-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 03/20/2023] [Indexed: 04/24/2023]
Abstract
As the first clinically translated machine-neural interface, cochlear implants (CI) have demonstrated much success in providing hearing to those with severe to profound hearing loss. Despite their clinical effectiveness, key drawbacks such as hearing damage, partly from insertion forces that arise during implantation, and current spread, which limits focussing ability, prevent wider CI eligibility. In this review, we provide an overview of the anatomical and physical properties of the cochlea as a resource to aid the development of accurate models to improve future CI treatments. We highlight the advancements in the development of various physical, animal, tissue engineering, and computational models of the cochlea and the need for such models, challenges in their use, and a perspective on their future directions.
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Affiliation(s)
- Filip Hrncirik
- Cambridge Hearing Group, Cambridge, UK.
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0QQ, UK.
| | - Iwan Roberts
- Cambridge Hearing Group, Cambridge, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - Ilkem Sevgili
- Cambridge Hearing Group, Cambridge, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - Chloe Swords
- Cambridge Hearing Group, Cambridge, UK
- Department of Physiology, Development and Neurosciences, University of Cambridge, Cambridge, CB2 3DY, UK
| | - Manohar Bance
- Cambridge Hearing Group, Cambridge, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0QQ, UK
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Dobrev I, Pfiffner F, Röösli C. Intracochlear pressure and temporal bone motion interaction under bone conduction stimulation. Hear Res 2023; 435:108818. [PMID: 37267833 DOI: 10.1016/j.heares.2023.108818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 05/16/2023] [Accepted: 05/25/2023] [Indexed: 06/04/2023]
Abstract
BACKGROUND Under bone conduction (BC) stimulation, the otic capsule, and surrounding temporal bone, undergoes a complex 3-dimentional (3D) motion that depends on the frequency, location and coupling of the stimulation. The correlation between the resultant intracochlear pressure difference across the cochlear partition and the 3D motion of the otic capsule is not yet known and is to be investigated. METHODS Experiments were conducted in 3 fresh frozen cadaver heads, individually on each temporal bone, resulting in a total of 6 samples. The skull bone was stimulated, via the actuator of a BC hearing aid (BCHA), in the frequency range of 0.1-20 kHz. Stimulation was applied at the ipsilateral mastoid and the classical BAHA location via a conventional transcutaneous (5-N steel headband) and percutaneous coupling, sequentially. Three-dimensional motions were measured across the lateral and medial (intracranial) surfaces of the skull, the ipsilateral temporal bone, the skull base, as well as the promontory and stapes. Each measurement consisted of 130-200 measurement points (∼5-10 mm pitch) across the measured skull surface. Additionally, intracochlear pressure in the scala tympani and scala vestibuli was measured via a custom-made intracochlear acoustic receiver. RESULTS While there were limited differences in the magnitude of the motion across the skull base, there were major differences in the deformation of different sections of the skull. Specifically, the bone near the otic capsule remained primarily rigid across all test frequency (above 10 kHz), in contrast to the skull base, which deformed above 1-2 kHz. Above 1 kHz, the ratio, between the differential intracochlear pressure and the promontory motion, was relatively independent of coupling and stimulation location. Similarly, the stimulation direction appears to have no influence on the cochlear response, above 1 kHz. CONCLUSIONS The area around the otic capsule appears rigid up to significantly higher frequencies than the rest of the skull surface, resulting in primarily inertial loading of the cochlear fluid. Further work should be focused at the investigation of the solid-fluid interaction between the bony walls of the otic capsule and the cochlear contents.
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Affiliation(s)
- Ivo Dobrev
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Zurich, University of Zurich, Frauenklinikstrasse 24, Zurich CH-8091, Switzerland.
| | - Flurin Pfiffner
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Zurich, University of Zurich, Frauenklinikstrasse 24, Zurich CH-8091, Switzerland
| | - Christof Röösli
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Zurich, University of Zurich, Frauenklinikstrasse 24, Zurich CH-8091, Switzerland
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O'Toole Bom Braga G, Zboray R, Parrilli A, Bulatović M, Caversaccio MD, Wagner F. Otosclerosis under microCT: New insights into the disease and its anatomy. FRONTIERS IN RADIOLOGY 2022; 2:965474. [PMID: 37492684 PMCID: PMC10365283 DOI: 10.3389/fradi.2022.965474] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 07/13/2022] [Indexed: 07/27/2023]
Abstract
Purpose Otospongiotic plaques can be seen on conventional computed tomography (CT) as focal lesions around the cochlea. However, the resolution remains insufficient to enable evaluation of intracochlear damage. MicroCT technology provides resolution at the single micron level, offering an exceptional amplified view of the otosclerotic cochlea. In this study, a non-decalcified otosclerotic cochlea was analyzed and reconstructed in three dimensions for the first time, using microCT technology. The pre-clinical relevance of this study is the demonstration of extensive pro-inflammatory buildup inside the cochlea which cannot be seen with conventional cone-beam CT (CBCT) investigation. Materials and Methods A radiological and a three-dimensional (3D) anatomical study of an otosclerotic cochlea using microCT technology is presented here for the first time. 3D-segmentation of the human cochlea was performed, providing an unprecedented view of the diseased area without the need for decalcification, sectioning, or staining. Results Using microCT at single micron resolution and geometric reconstructions, it was possible to visualize the disease's effects. These included intensive tissue remodeling and highly vascularized areas with dilated capillaries around the spongiotic foci seen on the pericochlear bone. The cochlea's architecture as a morphological correlate of the otosclerosis was also seen. With a sagittal cut of the 3D mesh, it was possible to visualize intense ossification of the cochlear apex, as well as the internal auditory canal, the modiolus, the spiral ligament, and a large cochleolith over the osseous spiral lamina. In addition, the oval and round windows showed intense fibrotic tissue formation and spongiotic bone with increased vascularization. Given the recently described importance of the osseous spiral lamina in hearing mechanics and that, clinically, one of the signs of otosclerosis is the Carhart notch observed on the audiogram, a tonotopic map using the osseous spiral lamina as region of interest is presented. An additional quantitative study of the porosity and width of the osseous spiral lamina is reported. Conclusion In this study, structural anatomical alterations of the otosclerotic cochlea were visualized in 3D for the first time. MicroCT suggested that even though the disease may not appear to be advanced in standard clinical CT scans, intense tissue remodeling is already ongoing inside the cochlea. That knowledge will have a great impact on further treatment of patients presenting with sensorineural hearing loss.
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Affiliation(s)
| | - Robert Zboray
- Center for X-ray Analytics, Swiss Federal Laboratories for Materials Science and Technology (Empa), Dübendorf, Switzerland
| | - Annapaola Parrilli
- Center for X-ray Analytics, Swiss Federal Laboratories for Materials Science and Technology (Empa), Dübendorf, Switzerland
| | - Milica Bulatović
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Marco Domenico Caversaccio
- Department of Otorhinolaryngology, Head and Neck Surgery, Inselspital, University Hospital Bern, Bern, Switzerland
| | - Franca Wagner
- Department of Diagnostic and Interventional Neuroradiology, Inselspital, University Hospital Bern, Bern, Switzerland
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